The present invention relates to a controller, particularly to a multi unit controller having a plurality of control units connected to each other to form a programmable controller, a system controller or the like.
JP-hei-7-200011-A discloses a multi unit controller capable of being easily modified to change control units incorporated into the controller so that a desired system size is easily obtainable. In this multi unit controller, each of base plates mounted on respective electrically insulating bases 61 has base connectors on its respective side surfaces, and a control unit connector, so that the bases of desired total number are juxtaposed transversely (substantially horizontally) to be electrically connected to each other, and a control unit is connectable to each of the control unit connectors mounted on the respective bases. Therefore, the control units electrically connected to each other through the bases electrically connected to each other can communicates with each other. Further, an external device can be connected to each of the control units through a terminal base mounted on the control unit and connected to an external electric line. A duct holds the external electric line.